Q:hi, i live in cape town and i would like to buy a solar panels for household use:lights,radio,tv and if possible iron and i don't know where to buy it or which one to buy.can i buy a +-15 watt or +-12 watt and with which invector can i use it with?

A:

We get this question a lot from people who are looking for a home solar panel system. They want to know how large their system needs to be, but that depends on how much energy you use, and you will need to do an energy audit to figure that out. And then you need to know how much sun you get where you live.

First, you need to determine how much energy you are consuming, Identify the appliances your using (light bulbs, radio, TV, etc) and find out the wattage consumed by each item. There should be a label on each appliance indicating its power consumption. For example, a typical 19-inch color TV consumes about 60 watts when running. Identify the wattage values of every appliance you want to power and apply the following formula:

Item x Quantity x Watts x Hrs/Day Used x Days/wk used ÷ 7 days = Watt Hours Consumed

Next, find out the number of peak sun hours (or daily insolation) your city receives. Cape Town is on the southern tip of Africa and it looks like it receives between 5 - 6.9hrs of peak sun. This is a considerable range so check some local resources.

Once you know the load you consume and the amount of peak sun you receive, you can calculate the size array needed. If you're just powering a TV, the size array needed would be estimated as follows:

TV x 1 x 60 watts x 4 hrs/day x 7 days/week ÷ 7 days = 240 watt-hrs /day, or .24kWh/day

If you receive 6 hrs of peak sun at your location, you would need (roughly) the following size array to power the TV:

.24kWh/day ÷ 6 hrs per day ÷ .88 PV Temp losses ÷ .84 derate factor ÷ .9 inverter efficiency = .06kW array

.06kW array x 1000watts/kilowatt = 60 PV array watts.

In this scenario a 60-watt panel would provide enough energy to offset the energy consumed by a 19-inch color TV. This answer assumes the solar energy system is grid-tied. Please do not assume that an appliance that there is a one-to-one match on watts consumed with watts on an array! That's just how this example worked out.

Find out how much energy you want to make and your local solar irradiation and we can specify a system to match this consumption.

08-10-2010 by france Category: Solar Panels

Q:Can TSM-220PA05 be used in a 12 volt system? I notice the voltage output is about 30 V. I hav a MPPT Charge Controller 15A, Wellsee WS-MPPT15 12V/24.

A:

The short answer is a qualified yes, because it depends on the solar charge controller. As long as it is a "step down" charge controller, it should be able to dial down the voltage to voltage level suitable for the batteries.Be sure to read the spec sheet on your charge controller! You may want to take a look at Outback FX models as well as the SolarBoost 50 that we offer. These charge controllers both have this capability.

07-28-2010 by Paul S Category: Solar Panels

Q:what harware do I need between a panel array and my house panel to do a net metering system. I am concerned that I don't have power to my panels from the grid and also that power company personnel are protected in the event of a general outage.

A:

If your current solar energy system is off grid, and needs to be changed to grid tie and connect with your local utility then it will require an inspection. It will also need to be connected to the grid through a grid tie inverter that feeds current into your breaker box via a circuit breaker or into the electric meter directly. All of the grid tie inverters SolarTown sells will shut-down in the event of a power outage. It sounds like you have an array that is DC only - the solar inverter is the item that changes the DC to AC and shuts down current in the event of a power outage. You will need to enter into a net metering agreement with your utility in order to send electricity onto the grid with your solar array. Contact your utility to find out what type of meter you currently have. Some meters will only run faster (and charge you more) if you hook an array up to them - so be sure you contact your utility and find out their requirements for net metering!

07-21-2010 by dave w Category: Solar Panels

Q:We are building a small cabin on a remote island and are thinking of using solar panels vice propane gas for stove and refrigerator. Neither has been purchased but would like good ball park estimate of 1) solar panel needs just for standard size family fridge and 2) solar power needs for both fridge and small 4 burner stove with oven.

A:

Commonly a refridgerator is one of the largest energy loads in the home. Be sure to choose an efficient one! If you are completely off grid then it likely makes sense to have the fridge use the same power source as the stove. Stoves and refridgerators have distinctly different tasks, and a propane stove makes more sense than an electric one. Electric stoves require a lot of electricity to run through their resistive burners. A propane stove may make the most sense.

Propane refridgerators are available but I have never used one. Electric fridges are getting more and more efficient, so when you shop for a fridge, make sure it has a very high R-value (insulation), a small current draw when operating, and separate freezer and fridge storage. Do not buy a side-by-side model. Make sure it is energy star rated, and the compressor is located on the top (this is why many freezers are on top - the freezer temperature naturally moves downward).

Propane is still carbon-based and won't turn on your lights for you. If the cabin is only being used a few times a year then you could easily power the rest of the cabin (and an electric fridge) with a 1 - 2kW solar energy system. The trick is installing solar modules in a good solar window with a reliable charge controller and deep cycle solar batteries with adequate amp-hour capacity. You don't want to show up at the cabin with solar batteries overcharged or out of power. If you're gone for months at a time you likely want to unplug the fridge when you leave.

It is important to select the most efficient products you can find so you know what they draw on a yearly basis. Once you know the loads the cabin will use (in watt-hours/day), we can specify a system to meet this need. Calculating electric loads is a matter of identifying the load (fridge, lights, radio) and how many watts they use on a daily basis. This can be gleaned from the yearly power estimate provided by the manufacturer and dividing this by 365 days per year. Contact us when you've identified the what appliances and other accessories you plan to use at the cabin. Enjoy the design process!

07-20-2010 by david Category: Solar Panels

Q:2400 sq ft house. What would be the total cost for a solar system for Air & Heating. Dallas TX. area. What systems should I consider.?

A: 

Every home is different and the size of your solar energy system will differ depending on what your needs are. We assume that you mean that you would like to purchase a solar energy system that would cover all of your electricity needs. You should first do an energy audit of your home and see how much electricity you are using and you will find that you should be able to take some relatively inexpensive measures. Through these energy audits you should be able to save as much as 30% of your electricity usage.  Then you should determine what your needs are. We are just assuming that your average monthly usage will be about 900 kWh per month. In Dallas, Texas, your solar radiance is approximately 5.3 kWh/sq. m/day. Your system size to cover 100% of your needs would be roughly 7 kW and you would need about 700 square feet on your foot to install this solar energy system. We offer discount solar panels in packages that could meet your needs. Please take a look at some of the solar package solutions we offer.

07-18-2010 by Doug P Category: Solar Panels

Q:Hi, I haven't even scratched the surface of your web site and have concluded that when I'm ready to install a solar system for electricity, I'll come to you folks. I've been reading in the Aks an Expert section and have come up with some very different or, shall I say, more technical questions. They are: 1. I noticed in one answer, you stated not to clean the panels with cold water, especially if and or when they are hot as they may crack. So, my question is: In the Summer here in TX, they would be HOT! and would they tend to crack if we had a thunderstorm? The rain that comes from those storms are usually very cold! 2. For the same storm scenario, It could develop and deliver large hail as they very often do here. Would hail damage the panels? Golf ball sized hail is common here. 3. You answered another question of mine and that was about the home owners insurance covering such damage. I'll be checking my insurance company to find that answer. When I do install a system, I'm looking for something in the 4k to 5k range. Many kudos for being such a helpful site! 

A:

Q1. Will solar modules crack in the event of a cold thunderstorm on an otherwise hot day in Texas?

A: Not likely. Solar panels are quite durable once they are installed. The biggest hazard is commonly when home solar panels are being installed - they won't fare well if dropped from a roof top. Solar panels are made to withstand high wind forces (5400 Pa is common) which is a measure of force per unit area. Panels are also made to endure severe weather conditions - wind, rain, sleet and snow. Weather variability is the main challenge for any solar panel as there are no moving parts (assuming a fixed mount installation). If panels cracked due to weather variations the solar industry would not be growing as quickly as it is.

Q2. Can hail damage solar panels?

A: Again, not likely - Solar modules have a layer of toughened glass something like your automobile windshield. And yes, windshields can crack - but do they crack in a hail storm? It may be possible, but  have never heard of this happening. More important, some manufacturers even detail their hail-impact ratings. Take a look at Sanyo's HIT Power 210 spec sheet - look at the operating conditions and safety ratings section at the end of the spec sheet. If a solar panel did crack in a hail storm, the manufacturer's warranty should cover the panel. Again, although it may be possible, I have never heard of a panel cracking due to a hail storm. Panels can get damaged though - but this is often such a calamity that your home owner insurance should cover it as more than just the panels might be damaged - perhaps a fire or a fallen tree that has damaged not only the solar array but the underlying structure. This of course depends on the insurance policy you have.

07-14-2010 by mntnman Category: Solar Panels

Q:I'm building a 35,000 square foot home. How many solar panels would i need for an average day of electricity?

A:

That is a very big house. You must be someone very famous and we offer discounts on all of our solar energy products to all of our famous customers. Only one minor problem. We assume that you probably have many other homes throughout the world, and so you probably don't live in this house. To conserve energy, you keep the electricity turned off most of the time, which we applaud. You may have a big house but if you never turn on the AC, your electricity usage is probably not very much. You may not be a good candidate for putting home solar panels on your roof. As a very rough rule of thumb, most systems are around 5 or 6kW for an average house. Your house is way over 10 times the average, so figure you should be thinking about a 60kW system or roughly 250-300 panels. We have some discount solar panels that we are sure would be ideal for your home.

06-26-2010 by Ashley Category: Solar Panels

Q:How many watts to run a 3 bedroom home?

A:

Every home is different and how much electricity you use depends on your individual habits and the condition of your home. In the US the average home consumes about 900 kwH per month. If you lived in the mid-Atlantic region, where you get about 4.5 peak sun hours per day, you would need a system of about 7 or 8 kW-you are looking at about 30 solar modules for your home. Most solar energy systems are sized not to absorb 100% of the electrical usage. If for example, you wanted to take care of 2/3 of your use, you would install about 20 home solar panels for your residence, and you would need roughly 500 square feet of roof space for these solar modules. We have a lot of information in the  SolarTown Learning Center  that you should read for more information.

06-21-2010 by Russell Category: Solar Panels

Q:which pump pumps the best (highest) psi rating.and how much solar watttage does it take. we have a number of livestock wells and they range in static 5gpm depth of 45feet down to 265 feet.?

A: 

There are many solar power water pumps available on the market today, and each has its own advantages and disadvantages. Based on your short description of the solar water pump system that you are looking for, the solar water pump that may suit your needs the best is the Lorrentz ECDRIVE 600. These submersible solar pumps
can handle volumes up to 20 gallons per minute and have a maximum lift of 250 feet. The amount of power determines the amount of output and lift. To meet your requirements, you would need to have approximately 300W of solar power to drive the pumps.

05-21-2010 by WWSVC Category: Solar Water Pumps

Q:What is the energy consumption of this solar water pump in watts.

A:

Please let us know which solar water pump you are referring to. Most of the solar power water pumps have a minimum wattage requirement before they will engage. However, based on your pumping requirements, in terms of distance and head, the wattage will vary. We would be happy to help you select the best solar water pump system to meet your requirements if you provide us with specifics.

05-16-2010 by Valentine A Category: Solar Water Pumps